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A User in the Volunteer API represents an individual person — typically a volunteer, but also organizers, administrators, and anyone else with a VOMO account. Users are the most commonly accessed resource for partner integrations: they’re queried for reporting, looked up by email for sync workflows, and created or updated when external systems push volunteer data into VOMO. This page covers the User resource in depth — the fields, the three endpoints, the list-vs-detail shape distinction, and the upsert behavior that makes POST /users distinctive.

The three endpoints

That’s the entire User write surface: one upsert endpoint that handles both create and update. There’s no separate PUT /users/{id} for updates.

The User resource

List shape (UserResource)

GET /users returns an array of UserResource objects — the abbreviated profile fields suitable for list display and filtering:

Detail shape (UserDetailResource)

GET /users/{id} returns a UserDetailResource — a superset of UserResource plus two additional fields: The UserDetailResource is what you get when you have a specific User and want the full picture. The UserResource is what you get when iterating through many Users for filtering or display.
⚠️ Spec gap: The OpenAPI spec’s UserDetailResource formally documents only participations and profile_field_values (audit #50 confirms the schema is sparse). In practice, the live API likely returns the base UserResource fields alongside these — making UserDetailResource a true superset, not a replacement. Confirm against actual responses for production-critical paths.

Membership concepts

Three status fields capture the User’s relationship to the customer’s organization:
⚠️ Spec gap (audit #45, #46): The spec types user_status, membership_status, and membership_role as string with no enum declared. The example values give hints (VERIFIED, ACCEPTED, VOLUNTEER), but the complete set of valid values is not documented.Code that switches on these values should handle unknown values gracefully — log them but don’t crash. The values are stable for known states but new states may be added over time.

Listing users

cURL

Available filters

All filters use snake_case. The *_like filters are case-insensitive substring matches. The *_before / *_after filters work on the corresponding timestamp fields.

Common list patterns

Recently active users:
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Users created in a specific time window:
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Find a user by email (one-shot):
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Note the explicit equality check — email_like is a substring match, so a search for bruce@wayne.example might match bruce@wayne.example.com if such an address exists. Confirm with strict equality after the API call.

Fetching a single user

cURL
Returns a UserDetailResource wrapped in data:
For workflows that already have the user ID, this is more efficient than filtering the list — one request, full detail, no pagination.
⚠️ Spec gap (audit #50): The spec types data on GET /users/{id} as type: array, but the live API returns a single object. Code should expect an object, not a single-element array.

Participations

The participations field on UserDetailResource is an array of the User’s participation records:
Each participation captures one User’s attendance at one Project Date. See The Volunteer Data Model: User ↔ Participation ↔ Project Date.
⚠️ Spec gap (audit #40, #41): hours is typed integer in the spec but returns fractional values (e.g., "4.00"). project_id and project_date_id are typed string but represent integer IDs. Parse hours as a float and the IDs as integers.

Profile field values

The profile_field_values field captures the User’s responses to custom profile fields configured in the customer’s VOMO account:
Each entry has a field_id (stable identifier), field_label (the human-readable name set in the admin UI), and value (the User’s response). For partner integrations that need to surface or filter on custom data, this is the access path. Look up by field_label for readability or by field_id for stability.

Creating and updating users (the upsert)

POST /users is unusual — it creates OR updates a User, with the behavior determined by whether the submitted email already exists.

How matching works

The match is on email. There’s no other way to identify the User for an update — no separate PUT /users/{id} exists.
⚠️ Spec gap (audit #47): The operationId is createUser but the endpoint is functionally an upsert. The spec correctly documents both 200 (updated) and 201 (created) response codes, but the operation name doesn’t reflect the upsert behavior. Future spec revisions may rename this to upsertUser and/or split into separate create and update endpoints.

The request

Detecting create vs. update

The response status code distinguishes the two cases:
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Many integrations care about the distinction — welcome emails should only fire on creation, sync logic may behave differently for new vs. existing users. The status code is the canonical signal.

Request body fields

Required fields for an upsert (typically — confirm against live API for the exact set): Optional fields:
⚠️ Spec gap (audit #44): The spec’s POST /users request body documents birthday with format: "YYYY-MM-DD" (not a valid OpenAPI format) and gender with format: "M|F|N" (not how enums are typically declared). The intent is clear (date in ISO format; gender enum), but SDK generators may struggle with these. Send ISO-8601 date strings for birthday and the documented enum values for gender.

Validation errors

If the request body fails validation (missing required fields, invalid email format, etc.), the API returns 422 Unprocessable Entity with a structured error response. See Error Handling: 422 Validation Error.
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Common workflows

Sync from an external system

For partner integrations syncing volunteer records from an external CRM or HR system:
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The same upsert call handles both new external records (creates the VOMO User) and updates to existing ones (updates the User). The integration doesn’t need separate code paths.

Bulk import

For one-time imports of volunteer rosters, throttle to stay within rate limits:
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Throttling matters for bulk imports — see Rate Limits.

Find or create

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This pattern is sometimes preferred over a blind upsert when you want explicit control over whether you’re creating or updating.

Calculate volunteer hours

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Note parseFloat(p.hours) rather than treating it as an integer — see the audit-flagged type issue.

What can’t be done via the API

For most of these, the customer’s admin team handles the action through the VOMO UI. See Understand Write Limitations for the broader picture.

ID and matching considerations

A few practical patterns for partner integrations:

Email is the matching key

Volunteer matches Users by email for upsert. Implications:
  • Email changes break matching. If a User changes their email in your external system, a subsequent upsert will create a new VOMO User rather than update the existing one. Track email history in your integration to handle this case.
  • Email case is normalized. Searches and matches are case-insensitive. Submit emails in any case; the API handles it.
  • Email is treated as the canonical identifier. Two records with the same email are considered the same person — there’s no way to have two Users with the same email.

Map between systems by both ID and email

For partner integrations that sync Users across systems, maintain a mapping table:
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Map by external ID → VOMO ID after the first successful upsert. Use the mapping for subsequent updates so email changes don’t break the linkage.

When IDs are unknown

If your integration needs to find a User but doesn’t have a VOMO ID: For programmatic flows where ambiguity is unacceptable, fall back to a surfaced-for-human-review path rather than guessing.

A reference user client

A minimal, well-organized User client:
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Where to go next

Projects and Project Dates

The volunteer opportunities Users participate in.

The Volunteer Data Model

The full data model context — how Users relate to other resources.

List Users with Filters

The workflow walkthrough for filtered User reads.

Create or Update a User

The upsert workflow in workflow-page depth.
Last modified on May 22, 2026